<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script>
        var age = 25;

        //typeof 判断基本数据类型
        console.log(typeof age); //number

        var name = "John";
        console.log(typeof name); //string

        var flag = true;
        console.log(typeof flag); //boolean
    </script>
</body>
</html>